android - 在 API 8 中使用加载器

Question

我正在学习 Lars Vogella 的教程:http://www.vogella.com/articles/AndroidSQLite/article.html#todo

但我希望它在 API 8 上运行。我让它在 API 11+ 上运行，并执行以下操作使其在 API 8 上运行。在 Android Tools 中，我添加了一个支持库，并添加了以下导入:

import android.support.v4.app.ListFragment;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.CursorLoader;
import android.support.v4.content.Loader;
import android.support.v4.widget.CursorAdapter;
import android.support.v4.widget.SimpleCursorAdapter;

但 Eclipse 仍然给我错误:

The method getLoaderManager() is undefined for the type TodosOverviewActivity

在方法中:

private void fillData() {

    // Fields from the database (projection)
    // Must include the _id column for the adapter to work
    String[] from = new String[] { TodoTable.COLUMN_SUMMARY };
    // Fields on the UI to which we map
    int[] to = new int[] { R.id.label };

    getLoaderManager().initLoader(0, null, this);
    adapter = new SimpleCursorAdapter(this, R.layout.todo_row, null, from,
        to, 0);

    setListAdapter(adapter);
  }

任何人都可以阐明这个错误吗？

---

我找到了以下“解决方案”，但我不确定如何在教程中实现它，这是使 getSupportLoaderManager() 和 ListView 相关方法可用的解决方案吗？如果是，我该如何正确实现它？ :

public class TodosOverviewActivity extends FragmentActivity {

public static class TodosOverviewListFragment extends ListFragment
        implements LoaderManager.LoaderCallbacks<Cursor> {

---

总类(class):

public class TodosOverviewActivity extends FragmentActivity implements
    LoaderManager.LoaderCallbacks<Cursor> {
  private static final int ACTIVITY_CREATE = 0;
  private static final int ACTIVITY_EDIT = 1;
  private static final int DELETE_ID = Menu.FIRST + 1;
  // private Cursor cursor;
  private SimpleCursorAdapter adapter;


/** Called when the activity is first created. */

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.todo_list);
    this.getListView().setDividerHeight(2);
    fillData();
    registerForContextMenu(getListView());
  }

  // Create the menu based on the XML defintion
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.listmenu, menu);
    return true;
  }

  // Reaction to the menu selection
  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case R.id.insert:
      createTodo();
      return true;
    }
    return super.onOptionsItemSelected(item);
  }

  @Override
  public boolean onContextItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case DELETE_ID:
      AdapterContextMenuInfo info = (AdapterContextMenuInfo) item
          .getMenuInfo();
      Uri uri = Uri.parse(MyTodoContentProvider.CONTENT_URI + "/"
          + info.id);
      getContentResolver().delete(uri, null, null);
      fillData();
      return true;
    }
    return super.onContextItemSelected(item);
  }

  private void createTodo() {
    Intent i = new Intent(this, TodoDetailActivity.class);
    startActivityForResult(i, ACTIVITY_CREATE);
  }

  // Opens the second activity if an entry is clicked
  @Override
  protected void onListItemClick(ListView l, View v, int position, long id) {
    super.onListItemClick(l, v, position, id);
    Intent i = new Intent(this, TodoDetailActivity.class);
    Uri todoUri = Uri.parse(MyTodoContentProvider.CONTENT_URI + "/" + id);
    i.putExtra(MyTodoContentProvider.CONTENT_ITEM_TYPE, todoUri);

    // Activity returns an result if called with startActivityForResult
    startActivityForResult(i, ACTIVITY_EDIT);
  }



  private void fillData() {

    // Fields from the database (projection)
    // Must include the _id column for the adapter to work
    String[] from = new String[] { TodoTable.COLUMN_SUMMARY };
    // Fields on the UI to which we map
    int[] to = new int[] { R.id.label };

    getSupportLoaderManager().initLoader(0, null, this);
    adapter = new SimpleCursorAdapter(this, R.layout.todo_row, null, from,
        to, 0);

    setListAdapter(adapter);
  }

  @Override
  public void onCreateContextMenu(ContextMenu menu, View v,
      ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    menu.add(0, DELETE_ID, 0, R.string.menu_delete);
  }

  // Creates a new loader after the initLoader () call
  @Override
  public Loader<Cursor> onCreateLoader(int id, Bundle args) {
    String[] projection = { TodoTable.COLUMN_ID, TodoTable.COLUMN_SUMMARY };
    CursorLoader cursorLoader = new CursorLoader(this,
        MyTodoContentProvider.CONTENT_URI, projection, null, null, null);
    return cursorLoader;
  }

  @Override
  public void onLoadFinished(Loader<Cursor> loader, Cursor data) {
    adapter.swapCursor(data);
  }

  @Override
  public void onLoaderReset(Loader<Cursor> loader) {
    // data is not available anymore, delete reference
    adapter.swapCursor(null);
  }

} 

Answer 1

问题是您要扩展“ListActivity”而不是“ListFragment”。

如果您利用 ListFragment，您将可以访问支持库中的 getLoaderManager()。

public class TodosOverviewActivity extends ListFragment {
  private void fillData() {
    getLoaderManager().initLoader(...);
  }
}